A brief discussion on anti-UV finishing of cotton fabrics
A brief discussion on anti-ultraviolet finishing of cotton fabrics
Abstract: With the improvement of living standards, people have higher and higher requirements for clothing materials. How cotton fabrics can resist ultraviolet radiation has become a research topic. This article mainly introduces several methods for anti-UV finishing of cotton fabrics.
Keywords; ultraviolet } cotton fabric;
Finishing: Long-term excessive ultraviolet rays cause photochemical reactions, which can cause a series of changes in human body functions, especially causing harm to human skin, eyes, and immune systems.
How to resist ultraviolet radiation in daily wear has become a direction of research on clothing materials.
1 The concept of ultraviolet rays Ultraviolet rays can be divided into UVA (wavelength 320-400nm), UVB (wavelength 290-320nm), and UVC (wavelength 180-290nm) according to their wavelength. UVC has high energy, but almost all of it is absorbed by the ozone layer and cannot reach the ground; UVB with relatively short wavelength and high energy can penetrate the skin for several millimeters, causing the skin to produce melanin, causing tanning and sunburn, and causing The skin is at risk of melanoma; UVA with longer wavelengths and smaller energy almost all reaches the ground, penetrates the skin, accelerates skin aging, and causes wrinkles and loss of elasticity of the skin. Therefore, UVA and UVB are the main targets of UV protection.
2 The relationship between ultraviolet rays and fabrics When ultraviolet rays are irradiated on fabrics, part of them is absorbed, part is reflected, and part is transmitted. Therefore, the higher the absorption rate and reflectivity, the lower the transmittance, and the better the protective performance. The UV transmittance of fabrics is affected by the structure of the fiber itself.
Different fiber types that make up fabrics have different ultraviolet transmittances. Cotton fabrics have relatively poor ultraviolet protection capabilities and are easy to penetrate ultraviolet rays. Wool and polyester have lower ultraviolet transmittances because of the polyester structure. The benzene ring and the aromatic amino acids in the wool protein structure have strong absorption of light smaller than 300nm.
3. Ultraviolet finishing methods of cotton fabrics. There are usually two methods for anti-UV finishing. One is to choose inorganic coatings that have a strong reflection effect on ultraviolet rays to achieve a shielding effect, such as zinc oxide and titanium dioxide; the other is to use ultraviolet absorbers. It absorbs light in the ultraviolet band and converts high-energy ultraviolet rays into heat energy and harmless low-energy radiation, such as salicylic acid, benzophenones, etc.
3.1 Use iron dioxide as a shielding agent [1] a. Reagent: titanium dioxide finishing agent prepared by sol-gel method. Received date: 2008-08-19 b. Fabric: pure cotton fabric C. Performance of finishing agent: The self-made nano-titanium dioxide anti-UV finishing agent has a very good anti-UV effect, especially it can shield all UVB area ultraviolet rays that are harmful to the human body. In the visible light region, the finishing agent has a high light transmittance and good transparency, making it suitable for printing and dyeing. d. Process flow: fabric two-dip and two-padding finishing solution (padding rate 70% to 80%) – inorganic salt solution treatment – drying (80℃*3min) – washing – drying (80℃*3min) )——Bei Bing e. Experimental results: By comparing the UV resistance, whiteness, breaking ability, and wrinkle recovery angle of the fabrics before and after treatment,
The following conclusions are drawn: ① The self-made nano-titanium dioxide anti-UV finishing agent has a good shielding effect on ultraviolet rays in the uVA and UVB bands. The anti-UV performance of cotton fabrics after finishing is significantly improved f ② Because of the inorganic salt concentration and baking time, the The whiteness of the fabric has little effect, but as the baking temperature increases, the whiteness of the fabric will decrease significantly. Therefore, the best finishing process for homemade nano titanium dioxide anti-UV finishing agent is: double immersion of the fabric – $L finishing liquid (padded liquid) Rate 70% – 80%) – 0.59/L inorganic salt solution treatment – drying (80℃*3min), two water washing – drying (100℃*2min) – baking, wrinkles of the fabric after finishing Recovery is somewhat reduced.
3.2 Nano-zinc oxide anti-UV finishing of cotton fabric is called a. Reagents: nano-ZnO, oligomeric sodium prenocrylate, water-soluble titanate coupling agent, NaOH b. Fabric: 1209/m2 bleached pure cotton khaki Cs process Process and finishing results: (The following amounts of raw materials are all experimental amounts) ① Take 0.59 water-soluble titanate coupling agent and add water to 50 mL. After stirring, add 0.759 nanometer zinc oxide and ultrasonic vibration; add 1-259 oligomer Sodium propenoate and NaOH were used to adjust the pH value of the solution to 9-10, and ultrasonic vibration was performed again. At this time, in the nano-zinc oxide dispersed system with the addition of sodium oligocrylate and coupled jade, the nano-zinc oxide Wanfang Data Yan Lei et al. briefly discussed the anti-ultraviolet finishing of cotton fabrics 23 The zinc is dispersed relatively evenly, without obvious “Cluster” phenomenon. Nano-zinc oxide basically remains within the nanoscale range.
② The fabric is finished by two immersions and two rollings (immersion temperature 20″C, liquid padding rate 80%), baked at 120-150″C for 30-150s, rinsed with clean water, dried at room temperature, and dried at 8.�Dry to constant weight in a constant temperature oven at 105°C. The finishing solution concentration is 1.09/L, the liquor ratio is 1.30, the soaking time is 150min, the baking temperature is 150℃, and after baking for 90s, the weight gain rate of the fabric is large. . As the weight gain rate increases, the ultraviolet transmittance of the fabric decreases. When the fabric weight gain rate is 4.64%, the average ultraviolet transmittance at 280-320nm is <3%. Therefore, when ensuring Under the premise that the nano-finishing liquid is evenly dispersed, the greater the weight gain rate of the fabric, the better the anti-ultraviolet effect of the fabric. After finishing, the hygroscopicity and strength of the fabric decrease slightly. Because the whiteness of nano-zinc oxide itself is very high, the fabric Whiteness increases after finishing.
3.3 Arrange cotton fiber into inorganic particles/cotton fiber composite material [3] a. Reagents: concentrated sulfuric acid (mass fraction 98%), barium chloride, ammonium dihydrogen sulfate, boric acid b. Fabric: cotton cloth c. Principle: Cotton fiber is a porous tissue, and its internal micropores (pores) have a diameter of only a few to more than ten nanometers, which can be used as a “microreactor” for the generation of nanoparticles.
When Ba2+ ions penetrate into the cotton fiber, it then reacts with PO. 3- Ion contact generates barium phosphate and barium hydrogen phosphate crystal precipitation in the micropores of the cotton fiber, thereby assembling the barium phosphate and barium hydrogen phosphate particles into the internal structure of the cotton fiber to form an inorganic ion/cotton fiber composite material. d. Process flow: cotton desizing – reagent treatment (first immersed in 60°C barium sulfide solution for 4 hours, then immersed in ammonium hydrogen phosphate solution for 4 hours) – padding – hot air drying (100°C) ) – Baking (150℃, 3-4min) – Soaping – Washing – Drying (105℃) – Finished product. e. Effect after treatment: ① The effect of treated cotton fabric after 12 washes The protection index UPF value reaches 17.7. This finishing agent can give cotton fabrics excellent and durable UV protection properties through simple padding and drying processes.
② Cotton fabric has strong UV protection properties.
3.4 Reactive anti-ultraviolet finishing agent UVDHA (the following drugs and fabrics are experimental quantities) [4] a. Fabric: pure cotton semi-finished products (30*30, 68*68) b. Reagent: anti-ultraviolet finishing agent UVDH ( Trichloropolyazine aromatic ammonia type), Modifier A (triazine amino stilbene type) C. Process principle: Reactive anti-ultraviolet finishing agent UVDH is a trichloropolyazine aromatic ammonium ultraviolet absorber with a water-soluble group Sulfonic acid group, ultraviolet absorbing group, ultraviolet absorbing group is an aromatic structure, and affinity substitution reaction occurs with nucleophiles such as hydroxyl anions of cellulose, water and other compounds: R 1 ^B—L ore rx” N T■Nang Hengcheng 爿. Improver A that has strong UVA absorption and replicates it into UVDHA, so that it can effectively absorb UVB while also absorbing UVA better, improving the overall ultraviolet protection effect. It can be selected with a triazine amino stilbene structure Improver, when combined with UVDH, it has better anti-UV finishing effect on pure cotton fabrics.
d. Process flow: Dye first, mix UVDH and improver A at a mass ratio of 6:1, emulsify through high-speed shearing and compound into UVDHA 3.5% (owl) suitable for pure cotton fabrics at a bath ratio of 1:20 , under the condition of 60℃, add sodium sulfate 609/L after 5 minutes to accelerate the absorption of the finishing agent, add sodium carbonate 159/L after 15 minutes, and raise the temperature (heating rate 2℃/min) to 85℃ to fix the finishing agent on the fiber. 30min, clean. e. Finishing results: ① After finishing, the UV protection performance is significantly improved compared to UVDH, the finishing efficiency is increased by 16.35%, the UPF value can reach 26.54, and the UPF grade is good according to AS/N ZS 4399; ② Fabric After UVDHA finishing, -OH and UVD on cotton fibers. The active groups on HA undergo nucleophilic substitution under alkaline conditions, resulting in a very stable covalent bond, so the fabric has good washing resistance; therefore, UVDHA is more suitable for white, yellow and blue cotton fabrics. UV protected finishing.
4 Conclusion With the gradual improvement of people’s living standards, the continuous enhancement of people’s self-protection awareness and the further deepening of labor protection work, anti-UV textiles have attracted more and more attention. As a purely natural textile, cotton fabric will be more and more popular among people. Using new methods and technologies to improve the UV resistance of cotton fabrics will have broad development prospects and good market potential.
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